There have been many nuclear logging technologies utilized in oil and gas wells in the past to evaluate the placement of gravel placed in a gravel packed interval of a wellbore, and cement placed in the annulus either between casing strings or between an outer casing and the borehole wall. Gravel pack evaluation oftentimes includes: (1) neutron or gamma ray count rates in conventional neutron logging tools employing neutron sources, (2) count rates and density measurements from gamma ray detectors in density-based logging tools with gamma ray sources, (3) detector count rates, silicon yields, and borehole capture cross section measurements from pulsed neutron logging tools, (4) gamma ray count rates from radioactive tracers (generated in a nuclear reactor) mixed and pumped downhole with the gravel pack material, and (5) yield and/or attenuation measurements from non-radioactive tracers added to, or integrated into, pack solids subsequently detected by neutron or pulsed neutron logging tools. Many of these nuclear technologies (in addition to conventional acoustic source-receiver based cement evaluation tools) have also been used to evaluate downhole cement placement. All of these techniques involve the use of fairly sophisticated logging tools using nuclear or acoustic sources, and in many cases, also involve the addition of radioactive or non-radioactive tracers to the gravel pack and cement slurries being pumped downhole. The use of tracers and/or sophisticated logging tools can add to the overall cost of a well.
There is a need, therefore, for a logging technique that does not require the use of sophisticated logging tools containing nuclear or acoustic sources. There is also a need for a logging technique that does not require the addition of tracers or tracer material to gravel pack or cement slurries.